In a prior-art clothespin, the two clamping levers are traversed by the cylindrical coil of a torsion spring and thus they are rotatably guided. The two spring ends extend with bent webs to the outer surface of the clamping jaws. Such a system is unsuitable for use when objects are to be clamped along a longer clamping line, as in the case of, e.g., the closing of open bags, containers and the like.
Clamps corresponding to German Utility Model DE-GM 89 12 654 are more suitable for the latter purpose, because they have clamping levers with elongated clamping jaws. These clamping levers are tensioned against each other by a leaf spring made in one piece with them, which entails the problem of generating a sufficiently strong clamping force.
Finally, it has been known from DE-A 36 23 766 that clamping levers consisting of plastic can be connected to the front-side ends of a clamp, which has the shape of a U and consists of spring steel. Even though a strong clamping force can be generated with such a clamp, the clamping line is relatively short. If one wished to increase the length of the clamping line of this prior-art clamp, which would automatically have to be accompanied by an increase in the length of the clamp, the resistance of the spring for spreading apart the clamp manually would be too high.
A clamp made of sheet metal parts, which is able to clamp and hold sheet-like objects as a consequence of an elongated clamping line, has been known from GB-A-26 73 26. The clamp has two clamping jaws, which are mounted on each other and have arched projections for surrounding a pivot pin located between them in the area of two support points located at spaced locations from one another. A hollow cylindrical, longitudinally slotted metal spring surrounds the individual support point and holds the clamping jaws together in a non-positive manner. In addition, a handle, formed by a bent wire, is hung on each clamping jaw under spring tension.
The prior-art clamp requires a considerable amount of tools and assembly due to its consisting of many parts, and it is susceptible to rusting.
DE-U-74 06 519 discloses a clothespin made of plastic, which has a relatively short, arched clamping surface on each clamping jaw, which forms one physical unit with the clamping lever associated with it. The clamping jaws are in contact with one another in the resting position, and they are secured against lateral displacement by a pin, which engages a recess. A U-shaped plastic clamp surrounds undercut projections of both clamping jaws, which have lateral recesses for inserting the plastic clamps.
This document fails to offer any suggestion on how sheet-like objects can be held along a long clamping line with the necessary clamping force.